New Q3 Engine exploit
It appears any cvar that is part of userinfo is susceptible to being too large and thus making the userinfo string bigger than 1024 (which would likely cause the IP string and others too may not then be retrieved with trap_GetUserinfo(...) as its not there because it was chopped off).
This can be a hazard because then ban checks cannot be performed. >.<
Fix: Well Luigi has a Windows only patch for it but I haven't heard it tested with q3 and its not supported by Linux.
Other possibilities: Enlarge the buffers in ClientConnect/ClientUserinfoChanged and check that its actual length is not greater than 1024. Check that there is indeed \ip\ in the string (You wouldn't want to also check for the value I guess because the value is lost after first connect.)